Hopewell Culture National Historical Park, Chillicothe, Ohio, has preserved 5 earth works, Mound City Group, Hopeton Earthworks, High Bank Works, Hopewell Mound Group, and Seip Earthworks from the Hopewell culture that flourished in the woodlands of eastern North America between 200 B.C. and A.D. 500. The Mound City Group also has an interesting museum with a collection of artifacts that is well worth seeing. The Ohio River Valley has been inhabited for over 12,000 years. http://www.nps.gov/hocu/http://www.stateparks.com/hopewell_culture.html